Sheet metal bending machine



` Dec. 65,1938.r w. L. CASTLE ET AL 2,139,354

SHEET METAL BENDING MACHINE Filed April 24, 1957 o I l F19. g l y 30 @umLeague-mndmgnedbe@" downwardly beneath the level oi the table, and

Patented Dec. 6, 1938 SHEET METAL BEND'ING MACHINE William L. Castle and William 0. Hedberg, Seattle, Wash., assignors to Boeing Aircraft Company, Seattle, Wash., a corporation of Washington Application April 24, 1937, Serial No. 138,785

7 Claims. (C1. 153-16) Our invention relates to a machine for bending sheet metal, and more particularly to a machine for bending or forming flanges on sheet metal plates or strips, which strips are other than straight, as for example structural elements or framing elements of aircraft.

Aircraft manufacture presents peculiar problems in that the corresponding parts of different airplanes must be interchangeable, and it must be possible to reproduce exactly any given element, to replace a damaged element, for instance, yet because they are manufactured in relatively small quantities, and because many parts are large--of considerable length, for instance it is impracticable to form these parts with complete punches and dies, as by stamping. It is necessary to form such elements as bent angles or channels, in a way and by means which will permit their exact reproduction in relatively small quantities, and at any time, and yet without the expense of making and storing the great number of dies and punches that would be required were such parts to be formed by a stamping operation, and it is to this object that our invention is primarily addressed.

As heretofore practiced it has been customary to employ a sheet metal bending machine in which a flat plate or strip to be flanged or bent is held down upon a work table or support by a presser head or die, and to act upon a flangeiorming part of the work by a movable head and die, oscillatable about an axis, termed the center of rotation, disposed substantially in the plane oi the under surface of the work as it rests upon the table, the bending being accomplished by localized iorce applied to the flange-forming part by the movable die to bend it progressively, both in degree and along the length of the work, until the work along its whole length is bent and formed to the shape desired, and determined by the cooperating iixed and movable dies. However, in order to gauge the point or line of bending it has been customary to provide a horn on the fixed die, curved about the center of rotation flange-forming portion a given distance from the line of the bend, though often in the nished product it made little difference if the height of the flange was greater or less than this distance, within considerable variations. The horn interfered to some extent with the forming operation since it took up part of the depth of the fixed die, along the line of closest approach of the two dies, and it necessitated that a complete new pair of heads be made and kept for each different part, for in addition to the normal variations in shape, curvature and contour of the dies, a die adapted for use in forming a flange of a given depth could not be used to form a flange of any diierent depth, since the edge of the flange was the gauge point, in cooperation with the horn. Of course, a flange of any given depth, formed by a given pair of dies, might be reduced in depth by cutting off the excess, but that again necessitated the extra operation of removing the excess portion of the flange after the bending operation was completed, which entailed additional labor and wastage of material. The wastage of material alone in the expensive materials used in aircraft constructiom'as also the wastage of skilled labor, would be matters of serious moment, so that this practice was not followed, but the wastage of labor required to form, to sto-re and to catalog the different dies and heads required for each different flange was a considerable item in the cost of manufacture of an airplane.

To remedy this condition we proposed to form the dies as elements which were separable from the respective heads, though still with the horn and recess, so that instead of storing the entire heads and removing them from the machine each time, it was possible to remove the dies only and to substitute other dies in their place. This lessened the cost of the operation to some degree, but still did not overcome the drawbacks attendant upon the use of the horn, namely, the necessity of forming the edge of the iiange-iorming part with extreme accuracy since it was to be used as a gauging edge, and it is the primary object of the present invention to eliminate these disadvantages, to retain the advantages of separable dies, and in general to provide a sheet metal bending machine which is readily adapted tothe work required, having the facility of forming duplicate parts at any time Without wastage of materials, Without preliminary work of extreme accuracy, and without the necessity of storing and cataloguing numerous dies or heads.

The invention comprises the novel machine and the novel parts thereof in their 'relative arrangeprojectinginto the path of themovable die, the latter being apertured for the reception of the horn. The edge oi the work was then placed against this horn and held thereagainst to gauge the point o1" bending inward from this edge. This procedure, however, had many disadvantages. It required nice calculation and extremely careful workmanship (the spacing varying with diiierent thicknesses of metal and different radii of curvature) to space the entire length of the edge of the ment and cooperative relationship, as shown in the accompanying drawings, described in this specification, and as will be more particularly defined by the claims which terminate the same.

In the accompanying drawing we have shown the pertinent parts of a sheet metal bending machine, in forms and relations which are now preferred by us, but we have omitted to disclose the driving or operating parts of such a machine since these are or may be the same as machines now known and commercially available, as shown for example in patent to Simmons, 2,025,360. It will be understood that the principles of our invention may be applied in various forms and relationships, and that those shown are for purposes of illustration only.

Figure 1 is a transverse section through the work, the two dies, and the table, and the gauging means associated therewith, showing parts in their operative relationship.

Figure 2 is an isometric View of the same parts except that the presser head and die is omitted for clearer illustration.

Such a sheet metal bending machine usually includes a table I which serves as a work support, a presser head 2 which is movable towards and from the upper surface of the table, as the movable head swings towards the work, to clamp the work W between itself and the table, and a movable head 3 which is oscillatable from a position beneath the surface of the table, as shown in Figure 2, into a position to bring a movable die carriedthereby into close proximity to the side face of a cooperating die carried upon the presser head 2. The center of this rotation, indicated at C. R., is customarily at the level of the upper surface of the table I Since these elements I, 2 and 3 are all part of known sheet metal bending machines, it is not deemed necessary to describe them in further detail, nor to illustrate the mechanism by which they are operated. Thus, for example, the presser head 2 may be moved vertically and guided by a post 2Q, and can be adjusted towards and from a vertical plane through C. R., and the movable head 3 may be oscillated by a link or other suitable element engaged within an apertured boss 3U, this boss and its operating connection moving upwardly through an aperture I in the table.

In accordance with one phase of the invention as explained above, there is secured upon the fixed head 2 a fixed die 4, removably held in place by suitable means typified by the bolt 24. Similarly, upon the movable head 3 is secured a movable die removably held in place by means typified by the bolt 35. The faces of these dies are usually relieved or convexed somewhat, so that they tend to engage along a vertical line, thereby accommodating work pieces which curve in either direction, but this line of contact of the movable die 5 is preferably aligned with and disposed substantially radially of the center of rotation C. R. The fixed die 4 with its presser head 2 is adjustable towards and from the vertical plane through the center of rotation, by means not shown, and is similarly adjustable towards and from the table I, to accommodate different thicknesses of sheet material. In our machine the function of the die 4, in addition to backing the lateral pressure transmitted to the flange-forming portion F of the work, and serving as a break for the corner, is to hold the Work W down upon the table during the bending operation.

The fixed die 4 has no function as a gauge, nor preferably has the die 5 any such function. Other gauging means, independent of the two dies, or at least independent of the die 4, are provided to engage the work, or a member fixed thereto, at a point other than the edge of the flange-forming portion F. Since the gauging will be more accurate as the point of gauging is adjacent the center of rotation C. R., we prefer that there be employed a template 6 which is securable temporarily to the work, preferably at its under side, by means such as the bolts and nuts at 60, and to guide this template we provide a guide lug 1, preferably formed as part of a removable block 10, inset into the table I and lying as close as is conveniently possible to C. R. Departing from previous sheet metal bending machines, the upper surface of the table I is depressed somewhat below the level of C. R., sufciently to accommodate the thickness of the template 6 and to again bring the under side of the work W into the horizontal plane occupied by the center of rotation, or substantially so. The lug 'I projects only sufficiently to engage the edge of the template 6, and should not extend above the level of the upper surface of the template. It should in most cases be of slight extent lengthwise of the work, and should lie in the line of closest approach of the two dies 4 and 5, so that the template, and consequently the work which is secured to the latter, is exactly gauged and guided in or as close as possible to the line of contact of the dies with the flange-forming portion F.

It may be pointed out that the engagement of the template by a lug positioned closely adjacent to C, R. is a matter of preference, rather than necessity. The template might be engaged by a guide or gauge otherwise located, and might indeed be disposed upon the upper surface of the work, or at a point distant from C. R. The essential feature of the invention is the employment of a template and a gauge therefor which are entirely independent of the die 4, at

least, and preferably of the dies 4 and 5, although A it might be pointed out that it is not outside the scope of our invention to form the `guide for the template as a part of the die 5.

By the arrangement described it is not essential that the flange-forming portion F have an accurately formed edge, or that its edge be at any precise distance from the point of the bend. The template is accurately formed at the outset, is secured to each piece of work to be operated upon by a temporary means easily engageable and disengageable, and the work is then run through the machine, transversely of the plane of swing of the die 5, in the usual manner, bending up the flange F progressively until it is bent to the proper angle to the web and has the proper contour, as determined by the cooperating faces of the dies 4 and 5. If, as is not usually the case, it is necessary to have the flange of exact depth, it can readily be out off before or after the flange has been formed. By cutting it off after the hanging operation, if any irregularities have crept in during the process of manufacture, and because of the folding or flowing of the metal, these are eliminated in this nal operation, but for most uses this is unnecessary, and the piece is completely formed with the completion of the bending operation.

Should it be desired to reproduce a piece later on it is only necessary to obtain the template from the storeroom. and since it is fiat, and a single piece only, it can be stored with a minimum of difficulty and space, and the workman can promptly produce the desired piece from the template and the blue print, and usually with a standard pair of dies. If the radius of the bend needs to be changed, it is only necessary to remove usually the die 4 and to replace it with a die having the correct radius of bend, but such changes are only such as are required by diiferences of material, contour, and radius of bend, and are never required because of differences in the depth of the flange.

What we claim as our invention is:

1. A machine for forming a flange on sheet metal pieces of different edge contours comprising a iiXed die and a movable die oscillatoryabout a center of rotation, a table with which the fixed die cooperates to hold down such a sheet of metal supported upon the table, with its mange-forming portion extending beyond the center of rotation into the path of the movable die, the table being depressed 'a given distance below the center of rotation, a template secured to and beneath such sheet of metal, of a thickness substantially equal to such depression of the table, and a template guide upstanding from the table sufficiently to engage the edge of the template, adjacent the center of rotation, as such template and the work are moved transversely of the plane of rotation of the movable die.

2. A machine for forming a flange on sheet metal pieces of different edge contours, comprising a xed die and a movable die oscillatory about a center of rotation, a table constituting a work support, having its upper surface depressed below the center of rotation, a template for securement to and beneath the work, to raise the under surface of the latter substantially to the level of the center of rotation, when the template rests upon the table, and a template guide xed relative to the center of rotation, and engageable with the template, and constituting the sole means, in cooperation with the template, to x the flange-forming portion of the work in position between the cooperating dies, as the template and work are moved transversely of the plane of rotation of the movable die.

3. A machine for forming flanges on sheet metal pieces of different edge contours, comprising a fixed die` and a movable die oscillatory about a center of rotation, a table constituting a work support with its upper surface disposed at a level no higher than the center of rotation, the xed die being devoid of any gauging element and engaging the work only upon its upper surface, at one side of the center of rotation, to hold the work to the table, and the movable die being likewise devoid of any gauging element and engaging the flange-forming portion of the work only upon its initially under side, at the opposite side of the center of rotation, and gauge means independent of the two dies and including a member secured to the work to position the ange-forming portion of the work between such dies, as the work is moved transversely of the plane of rotation of the movable die.

4. A machine for forming flanges on sheet metal pieces of different edge contours, comprising a fixed die and a movable die oscillatory about a center of rotation, a table constituting a work support with its upper surface disposed at a level not higher than the center of rotation, the iixed die being devoid of any gauging element and engaging the Work only upon its upper surface, at one side of the center of rotation, to hold the work to the table, and the movable die engaging the flange-forming portion of the work only upon its initially under side, at the opposite side of the center of rotation, and gauge means independent of the fixed die, and including a member secured to the work to position the iange-forming portion of the work between such dies, as the work is moved transversely of the plane of rotation of the movable die.

5. A machine for forming flanges on sheet metal pieces of diiferent edge contours, comprising a fixed die and a movable die oscillatory about a center of rotation, a table constituting a work support with its upper surface disposed at a level not higher than the center of rotation, the fixed die being devoid of any gauging element and engaging the work only upon its upper surface at one side of the center of rotation, to hold the work to the table, and the movable die engaging the flange-forming portion of the work only upon its initially under side, at the opposite side of the center of rotation, a template secured to the work, and a template guide independent of the xed die, cooperating and constituting the sole means to position the flange-forming portion of the work between the two dies, as the template and work are moved transversely of the plane of rotation of the movable die.

6. A machine for formingv flanges on sheet metal pieces of different edge contours, comprising a table constituting a work support, a presser head above and movable towards and from the table, a xed die removably secured upon the presser head, a movable head oscillatory about a center of rotation which is at a level adjacent the level of the table top, a movable die removably secured upon the movable head, and formed to cooperate with the fixed die, the xed die being engageable only with the upper surface of the work resting upon the table, and at one side of' the center of rotation, and the movable die being engageable only with the initially under side or the ange-forming portion of the work, at the opposite side of the center of rotation, and gauge means independent of the xed die, and including a template secured to the work to position the flange-forming portion of the work between such dies, as the work and template are moved transversely of the plane of rotation of the movable die.

7. A machine for forming a flange upon a sheet metal piece, comprising a table, a template fixed to the work piece, and having an edge accurately formed to the desired contour of the flange, a template guide engageable by such template edge as the template and work are shifted lengthwise along the table, a fixed die separate from the template, cooperating with the table to hold the work piece upon the table, and having a surface shaped to form the ange, and amovable die separate from the template, engageable with the initially lower face of the flange-forming portion of the work piece, and cooperating with the fixed die to form successive local areas of the ange to an angle determined solely by the two dies, but to a contour determined solely by the template, in conjunction with its guide.

WILLIAM L. CASTLE. WILLIAM O. I-IEDBERG. 

